LONDON, England (CNN) -- An online petition demanding a formal apology from the British government for its treatment of World War II code-breaker Alan Turing is gaining momentum.

A portrait of Alan Turing is currently on display at the National Portrait Gallery's "Gay Icons" exhibition.

Turing was subjected to chemical castration in 1952 after being found guilty of the charge of gross indecency for having a homosexual relationship, an illegal act at the time. He committed suicide two years later.

More than 19,000 people have added their names to the petition on the UK Government Web site since it opened three weeks ago, urging the government to "recognize the tragic consequences of prejudice that ended this man's life and career."

The petition was created by computer scientist John Graham-Cumming, who said he grew "mad" at the country's memory of a man he says should be considered one of its national heroes.

"I'm looking for an apology from the British government because that's where I think the wrong was done. But Turing is clearly someone of international stature," Graham-Cumming said.

Turing was best known for inventing the Bombe, a code-breaking machine that deciphered messages encoded by German Enigma machines during World War II.

The messages provided the Allies with crucial information from the British government's code-breaking headquarters in Bletchley Park where Turing worked full-time during the war.

He was considered a mathematical genius and went on to develop the Turing machine, a theory that automatic computation cannot solve all mathematical problems, which is considered the basis of modern computing.

However, to avoid a custodial sentence for gross indecency Turing agreed to undergo chemical castration. He was injected with estrogen, an experience that is widely believed to have led to his suicide just two years later. Turing was just 41 when he ended his life by eating an apple laced with cyanide.

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Graham-Cumming has not yet received a response from the British government to his request for an apology, nor has he received a reply from Queen Elizabeth II to whom he wrote last week asking that Turing be considered for a posthumous knighthood.

"There is no doubt in my mind," he wrote, "that if Turing had lived past age 41 his international impact would have been great and that he likely would have received a knighthood while alive."

Graham-Cumming's efforts to draw attention to Turing's life has attracted an international response.

"This morning I woke up to an inbox stuffed full of e-mails and blog postings from around the world on Turing, and many people were saying 'it's a pity I can't sign the British petition,'" he said. The main online petition is only open to British citizens.

Graham-Cumming said if the government would not extend an apology, "the least it could do is to put Bletchley Park on a sound financial footing in Turing's name."

Earlier this year, the center's supporters created their own online petition urging the government to "save Bletchley Park."

The site receives no external funding and has been turned down for funds by the UK National Lottery, and the Bill and Melinda Gates Foundation.

The government replied to the petition last week saying that, while it "agrees that the buildings on the Bletchley Park site are of significant historic importance and, although recognizing the excellent work being carried out there, at present it has no plans, nor the resources, to extend its sponsorship of museums and galleries beyond the present number."

Simon Greenish, director of the Bletchley Park Trust, said: "The work that Turing did during the war has never really been properly recognized and this is an opportunity [for the government] to do that."

He said the government had also failed to recognize the contribution of Bletchley Park to the war effort: "What went on in those buildings was absolutely vital to the outcome of World War II."

The center receives more than 100,000 visitors a year and is staffed mainly by volunteers.

A portrait of Turing is currently on display at the National Portrait Gallery in London, as part of its "Gay Icons" exhibition. He was one of the six personal icons selected by contributor Chris Smith, Britain's first openly gay Member of Parliament.